9.2.2　Antioxidants

Clinical commonly used antioxidants include fruit acid，salicylic acid and so on.Fruit acid was introduced into the field of skin treatment in 1974 for the treatment of ichthyosis.It refers to a class of alpha hydroxyacids，which is a family including glycolic acid，tartaric acid，citric acid，lactic acid，etc.Salicylic acid，as a chemical peeling agent for the skin，was originally extracted from willow bark.Topical treatment with salicylic acid or fruit acid can significantly improve erythema，inflammatory papules and pigmentation.The mechanism is that when the antioxidant is applied to the skin，fruit acid activates the cell ion channel TRPV3，and excessive calcium ions enter the cells to induce apoptosis，thus softening the stratum corneum and accelerating the exfoliation of the stratum corneum，so that the melanin in the keratinocytes is exfoliated together，and a lighter skin color reveals.Long-term use can stimulate the synthesis of collagen and mucopolysaccharide in the dermis，which will lighten the skin wrinkle，and it is better for the wrinkle caused by photoaging skin（due to the degeneration and reduction of collagen in the dermis）.In addition，the use of antioxidants can soften keratin and promote drug penetration，thereby improving the efficacy of external medicine.(https://www.daowen.com)